Backend Engineer - Recommendation (all genders)
About You SE & Co. KG4 days ago
Hamburg, Germany or Berlin, GermanyMid Level
Responsibilities
- Develop the recommendation engine powering ABOUT YOU’s homepage, product pages, and outfit pages.
- Serve offline-trained models, including matrix factorization, brand similarity, and image-embedding models.
- Build personalization logic for feed assembly, fallback chains, deduplication, diversity, and A/B experimentation.
- Build streaming GenAI product features such as the Gemini fashion advisor, with attention to latency, session state, and token costs.
- Own reverse-ETL pipelines that move BigQuery model outputs into high-performance hot stores.
- Instrument recommendation coverage and track business metrics through SQS and BI systems.
- Shape system architecture alongside the Tech Lead and take end-to-end ownership of the recommendation engine.
Requirements
- At least 3 years of experience building high-throughput backend services.
- Experience with Node.js and TypeScript, or the ability to transition quickly from Java, Go, or Kotlin.
- Deep experience with Redis or Valkey data modeling, multi-tier caching, TTLs, invalidation, and binary payloads such as Protobuf or Avro.
- Experience operating APIs at 10k+ requests per second under strict latency SLOs.
- Interest or experience in serving model scores, embeddings, or LLM features in live systems.
- Clear English communication and a data-driven, experiment-friendly mindset.
- Preferred: recommender-system fundamentals including collaborative filtering, matrix factorization, cold-start handling, and diversity algorithms.
- Preferred: streaming GenAI or LLM product experience, including chat UX, prompt caching, and guardrails.
- Preferred: AWS serverless experience, DynamoDB modeling, SQS/SNS, and OpenSearch k-NN indices.
- Preferred: performance profiling with clinic.js or flamegraphs and load testing with k6.
Benefits
- The company emphasizes an inclusive workplace where people can bring different backgrounds and perspectives.
- The culture highlights flat hierarchies, direct communication, pragmatic decisions, ownership, trust, and clear responsibility.
- Team activities include team lunches, afterwork drinks, company events, and informal coffee breaks.
- Applicants apply online through the company career page; additional benefits are referenced on the company benefits page.
Categories
About About You SE & Co. KG
ABOUT YOU SE & Co. KG operates an online fashion marketplace for European consumers and licenses commerce technology to brands via its SCAYLE platform. The group sells apparel and lifestyle products through its mobile app and aboutyou.com, and offers a cloud-based enterprise shop system under a license model to retailers. Founded in 2014 and headquartered in Hamburg, it is a publicly listed company.